1. Field of the Invention
The present invention relates to a terminal device and a network setting method therefor, a service providing device and an operation control method therefor, a network system, and a program.
2. Description of the Related Art
Heretofore, devices that are connected to networks are primarily PCs (Personal Computers).
In recent years, it has become possible to connect service providing devices to networks. A service providing device is a device for providing a certain service to a PC. For example, a service providing device comprises a peripheral device such as a printer, a scanner, a projector, or the like. Therefore, a peripheral device (service providing device) serves as a network terminal device.
In order for a PC to use a service provided by a peripheral device through a network, a network environment needs to be given to the PC and the peripheral device. The network environment includes IP addresses of the PC and the peripheral device.
An IP address is assigned to a device connected to a network mainly by a DHCP (Dynamic Host Configuration Protocol) server (automatic address assigning device).
Heretofore, various DHCP servers have been proposed in the art.
For example, document 1 (Japanese laid-open patent publication No. 2003-143175) discloses a DHCP server that stops an automatic address assigning service if another DHCP service is present on the network.
Document 2 (Japanese laid-open patent publication No. 2002-164904) discloses a DHCP server system having two DHCP servers connected to a network. On the DHCP server system, one of the two DHCP servers performs its DHCP server operation, and the other waits in readiness. When the operating DHCP server suffers a failure, the other comes in and performs its DHCP server operation.
A PC and a peripheral device may not necessarily be connected to a network at all times, but may be highly likely to be given different IP addresses by the DHCP server system disclosed in document 1 or 2 each time they are connected to the network. Therefore, any PCs and peripheral devices that are not connected to the network at all times, find it difficult to accurately recognize at all times an IP address that is assigned to a device with which they are to communicate.
When a user connects the peripheral device to a network, the user has to change the IP address of the peripheral device or the PC, which uses a service provided by the peripheral device, so that the peripheral device and the PC can properly recognize each other's IP addresses.
Some existing peripheral devices assign a network address to a PC with which they are to communicate when they are connected to a network. The network address assigned to the PC by such a peripheral device may differ from one given by an address assigning system of the network, e.g., an IP address assigned to the PC by a DHCP server that is connected to the network.
If the PC uses the IP address assigned thereto by the DHCP server, then the PC is unable to communicate with the peripheral device. Consequently, the user needs to change the IP address of the peripheral device or the IP address of the PC. IP addresses have to be changed each time the peripheral device is connected to the network.
Some existing DHCP servers assign an IP address to only specific network devices. If such a DHCP server is used, then the user has to assign an IP address to a network device to which an IP address has not been assigned by the DHCP server. The user finds it tedious and time-consuming to assign an IP address to the network device when the network device is connected to the network.
Specifically, the user is required to have professional knowledge in order to assign an IP address to a PC or to a peripheral device. In addition, the user may possibly make a mistake by assigning one IP address to a plurality of devices when assigning an IP address to a PC or to a peripheral device.